* [PATCH] kprobes: avoid the kprobe being re-registered
@ 2017-10-26 12:11 Zhou Chengming
2017-10-26 14:39 ` Masami Hiramatsu
0 siblings, 1 reply; 3+ messages in thread
From: Zhou Chengming @ 2017-10-26 12:11 UTC (permalink / raw)
To: ananth, anil.s.keshavamurthy, davem, mhiramat
Cc: linux-kernel, zhouchengming1
Old code use check_kprobe_rereg() to check if the kprobe has been
registered already, but check_kprobe_rereg() will release the
kprobe_mutex then, so maybe two paths will pass the check and
register the same kprobe. This patch put the check inside the mutex.
Signed-off-by: Zhou Chengming <zhouchengming1@huawei.com>
---
kernel/kprobes.c | 23 ++++++-----------------
1 file changed, 6 insertions(+), 17 deletions(-)
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index a1606a4..2a4873a 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1443,19 +1443,6 @@ static struct kprobe *__get_valid_kprobe(struct kprobe *p)
return ap;
}
-/* Return error if the kprobe is being re-registered */
-static inline int check_kprobe_rereg(struct kprobe *p)
-{
- int ret = 0;
-
- mutex_lock(&kprobe_mutex);
- if (__get_valid_kprobe(p))
- ret = -EINVAL;
- mutex_unlock(&kprobe_mutex);
-
- return ret;
-}
-
int __weak arch_check_ftrace_location(struct kprobe *p)
{
unsigned long ftrace_addr;
@@ -1536,10 +1523,6 @@ int register_kprobe(struct kprobe *p)
return PTR_ERR(addr);
p->addr = addr;
- ret = check_kprobe_rereg(p);
- if (ret)
- return ret;
-
/* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */
p->flags &= KPROBE_FLAG_DISABLED;
p->nmissed = 0;
@@ -1551,6 +1534,12 @@ int register_kprobe(struct kprobe *p)
mutex_lock(&kprobe_mutex);
+ /* Return error if the kprobe is being re-registered */
+ if (__get_valid_kprobe(p)) {
+ ret = -EINVAL;
+ goto out;
+ }
+
old_p = get_kprobe(p->addr);
if (old_p) {
/* Since this may unoptimize old_p, locking text_mutex. */
--
1.8.3.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] kprobes: avoid the kprobe being re-registered
2017-10-26 12:11 [PATCH] kprobes: avoid the kprobe being re-registered Zhou Chengming
@ 2017-10-26 14:39 ` Masami Hiramatsu
2017-10-27 1:24 ` zhouchengming
0 siblings, 1 reply; 3+ messages in thread
From: Masami Hiramatsu @ 2017-10-26 14:39 UTC (permalink / raw)
To: Zhou Chengming; +Cc: ananth, anil.s.keshavamurthy, davem, linux-kernel
On Thu, 26 Oct 2017 20:11:25 +0800
Zhou Chengming <zhouchengming1@huawei.com> wrote:
> Old code use check_kprobe_rereg() to check if the kprobe has been
> registered already, but check_kprobe_rereg() will release the
> kprobe_mutex then, so maybe two paths will pass the check and
> register the same kprobe. This patch put the check inside the mutex.
Still no good, see below comment.
>
> Signed-off-by: Zhou Chengming <zhouchengming1@huawei.com>
> ---
> kernel/kprobes.c | 23 ++++++-----------------
> 1 file changed, 6 insertions(+), 17 deletions(-)
>
> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> index a1606a4..2a4873a 100644
> --- a/kernel/kprobes.c
> +++ b/kernel/kprobes.c
> @@ -1443,19 +1443,6 @@ static struct kprobe *__get_valid_kprobe(struct kprobe *p)
> return ap;
> }
>
> -/* Return error if the kprobe is being re-registered */
> -static inline int check_kprobe_rereg(struct kprobe *p)
> -{
> - int ret = 0;
> -
> - mutex_lock(&kprobe_mutex);
> - if (__get_valid_kprobe(p))
> - ret = -EINVAL;
> - mutex_unlock(&kprobe_mutex);
> -
> - return ret;
> -}
> -
> int __weak arch_check_ftrace_location(struct kprobe *p)
> {
> unsigned long ftrace_addr;
> @@ -1536,10 +1523,6 @@ int register_kprobe(struct kprobe *p)
> return PTR_ERR(addr);
> p->addr = addr;
>
> - ret = check_kprobe_rereg(p);
> - if (ret)
> - return ret;
> -
> /* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */
> p->flags &= KPROBE_FLAG_DISABLED;
> p->nmissed = 0;
here, we already modifies the kprobe. We need to check and reject before modifying it.
Thank you,
> @@ -1551,6 +1534,12 @@ int register_kprobe(struct kprobe *p)
>
> mutex_lock(&kprobe_mutex);
>
> + /* Return error if the kprobe is being re-registered */
> + if (__get_valid_kprobe(p)) {
> + ret = -EINVAL;
> + goto out;
> + }
> +
> old_p = get_kprobe(p->addr);
> if (old_p) {
> /* Since this may unoptimize old_p, locking text_mutex. */
> --
> 1.8.3.1
>
--
Masami Hiramatsu <mhiramat@kernel.org>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] kprobes: avoid the kprobe being re-registered
2017-10-26 14:39 ` Masami Hiramatsu
@ 2017-10-27 1:24 ` zhouchengming
0 siblings, 0 replies; 3+ messages in thread
From: zhouchengming @ 2017-10-27 1:24 UTC (permalink / raw)
To: Masami Hiramatsu; +Cc: ananth, anil.s.keshavamurthy, davem, linux-kernel
On 2017/10/26 22:39, Masami Hiramatsu wrote:
> On Thu, 26 Oct 2017 20:11:25 +0800
> Zhou Chengming<zhouchengming1@huawei.com> wrote:
>
>> Old code use check_kprobe_rereg() to check if the kprobe has been
>> registered already, but check_kprobe_rereg() will release the
>> kprobe_mutex then, so maybe two paths will pass the check and
>> register the same kprobe. This patch put the check inside the mutex.
> Still no good, see below comment.
>
>> Signed-off-by: Zhou Chengming<zhouchengming1@huawei.com>
>> ---
>> kernel/kprobes.c | 23 ++++++-----------------
>> 1 file changed, 6 insertions(+), 17 deletions(-)
>>
>> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
>> index a1606a4..2a4873a 100644
>> --- a/kernel/kprobes.c
>> +++ b/kernel/kprobes.c
>> @@ -1443,19 +1443,6 @@ static struct kprobe *__get_valid_kprobe(struct kprobe *p)
>> return ap;
>> }
>>
>> -/* Return error if the kprobe is being re-registered */
>> -static inline int check_kprobe_rereg(struct kprobe *p)
>> -{
>> - int ret = 0;
>> -
>> - mutex_lock(&kprobe_mutex);
>> - if (__get_valid_kprobe(p))
>> - ret = -EINVAL;
>> - mutex_unlock(&kprobe_mutex);
>> -
>> - return ret;
>> -}
>> -
>> int __weak arch_check_ftrace_location(struct kprobe *p)
>> {
>> unsigned long ftrace_addr;
>> @@ -1536,10 +1523,6 @@ int register_kprobe(struct kprobe *p)
>> return PTR_ERR(addr);
>> p->addr = addr;
>>
>> - ret = check_kprobe_rereg(p);
>> - if (ret)
>> - return ret;
>> -
>> /* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */
>> p->flags&= KPROBE_FLAG_DISABLED;
>> p->nmissed = 0;
> here, we already modifies the kprobe. We need to check and reject before modifying it.
>
> Thank you,
Ah, right. We should put the modifies after the re-reg check. I will send a patch-v2.
Thank you.
>> @@ -1551,6 +1534,12 @@ int register_kprobe(struct kprobe *p)
>>
>> mutex_lock(&kprobe_mutex);
>>
>> + /* Return error if the kprobe is being re-registered */
>> + if (__get_valid_kprobe(p)) {
>> + ret = -EINVAL;
>> + goto out;
>> + }
>> +
>> old_p = get_kprobe(p->addr);
>> if (old_p) {
>> /* Since this may unoptimize old_p, locking text_mutex. */
>> --
>> 1.8.3.1
>>
>
^ permalink raw reply [flat|nested] 3+ messages in thread
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